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kernel: add do_compat_sigaltstack() helper; remove in-kernel call to compat syscall 

Using this helper allows us to avoid the in-kernel call to the
compat_sys_sigaltstack() syscall.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski 2018-03-17 17:11:51 +01:00
parent 192c58073d
commit 6203deb0a7
1 changed files with 10 additions and 4 deletions
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14
kernel/signal.c
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@ -3573,9 +3573,8 @@ int __save_altstack(stack_t __user *uss, unsigned long sp)
}
#ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(sigaltstack,
const compat_stack_t __user *, uss_ptr,
compat_stack_t __user *, uoss_ptr)
static int do_compat_sigaltstack(const compat_stack_t __user *uss_ptr,
compat_stack_t __user *uoss_ptr)
{
stack_t uss, uoss;
int ret;
@ -3602,9 +3601,16 @@ COMPAT_SYSCALL_DEFINE2(sigaltstack,
return ret;
}
COMPAT_SYSCALL_DEFINE2(sigaltstack,
const compat_stack_t __user *, uss_ptr,
compat_stack_t __user *, uoss_ptr)
{
return do_compat_sigaltstack(uss_ptr, uoss_ptr);
}
int compat_restore_altstack(const compat_stack_t __user *uss)
{
int err = compat_sys_sigaltstack(uss, NULL);
int err = do_compat_sigaltstack(uss, NULL);
/* squash all but -EFAULT for now */
return err == -EFAULT ? err : 0;
}